ABSTRACT
The trophic consequences of the apparent global increase in the frequency of coastal red-tide blooms and spreading of toxic and benign phytoplankton species into new regions are considered. Various mechanisms are described by which blooms of red-tide species can negatively impact, lead to dysfunction in, and alter trophodynamics in all trophic compartments, from the microbial food web up to marine mammals. Reduced fecundity, survival and recruitment, and increased mortality of first feeding, juvenile, and adult stages can result from toxins produced by red-tide species, having either a direct impact upon or vectoring through the food web. The classical notion that red-tide blooms are insignificant to trophodynamics, and of interest primarily because of their impact on humans through paralytic shellfish poisoning, or economically from aquacultural dieoffs, is invalid. A trophic model showing the routing of toxins and inimical phytoplankton effects through the various trophic compartments of marine food webs is presented. Two major types of negative events can accompany nuisance blooms: water column events, usually associated with toxin production, and anoxic events which accompany benthic accumulation; and respiration of blooms which are underutilized by grazers. The potential consequences of the altered red-tide bloom characteristics in coastal waters to larval survival and recruitment of fish which have synchronized their spawning cycle strategies to phytoplankton bloom characteristics are touched upon. Assessments of the causes of variability at different life history stages of fish must include consideration of red-tide events and toxic species occurrences.
